This invention relates to pivotable linkage devices and more particularly to such a linkage device that is capable of pivoting a supported member, such as a payload, between stowed and operating positions on the end of a supporting member.
The use of communications and various electronic and optical equipment, herein referred to as payloads, in hostile military environments often requires erecting antennas and the like as high as 20 meters or more above ground in order to facilitate transmission and reception of signals to and from distant locations. A telescopic mast useful for deploying such payloads is described in U.S. application Ser. No. 246,112. During such deployment, the payload is moved from a stowed position, usually offset from the mast axis, to an operative position extending outwardly from and axially aligned with the mast. To facilitate rapid deployment, the payload may be pivotally connected to the end of the mast tube by a linkage device.
Prior linkage devices of this type usually have a single pivot point hinge or a rotator mechanism that keeps the payload axis offset from the mast tube axis after deployment. The single pivot point hinge requires gear reduction apparatus that is heavy and also needs separate braking/locking devices, all of which are costly. The problem with the offset axis design is that it tends to eccentrically load the whole system. Eccentric loading exaggerates deflections and results in an inherently weaker design. In addition to this, the deploying axis swings horizontally about a vertical axis to position the load. While this precludes the need for a large gear box, it requires a considerable amount of horizontal room, thereby eliminating its use in applications where horizontal space is absent or limited.
This invention is directed to a linkage device which eliminates and avoids these difficulties and disadvantages.